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Technical > Engines > Flashcards

Engines Flashcards

1
Q

What is on the accessory gearbox?

A
  • Oil feed pump
  • Main engine fuel pump (combustion chamber)
  • Hydraulic pumps
  • Generators
  • FADEC alternator
  • Pneumatic starter
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2
Q

What does the FADEC control?

What two parameter protections are there?

A
  • Fuel flow
  • Accel / decel schedules
  • Variable bleed valve and stator vanes
  • Turbine clearance
  • Idle
    • Modulated (bleed/ambient) - flight (clean) or ground
    • Approach idle- allows rapid accel
    • Reverse Idle- slightly higher than normal idle
  • Fuel circulation (IDG)
  • N1 / 2 overspeed
  • EGT during start
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3
Q

What does the Hydromechanical Unit do?

What meters fuel to the nozzles?
What gives fuel flow feedback to FADEC?

How is the pressure drop kept constant across the FMV?

A

FF
Fuel hydraulic signals to actuators
Stops overspeeding

Fuel Metering Valve FRV
FMV resolver

Via bypass valve (directs fuel to FRV)

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4
Q

What does FADEC control to manage N1?

FADEC control parameters to achieve what?

A

Controls FF
* allows N2 to vary*
Ensures FF reading is proportional to FMV position

  • limit accel/decel
  • avoid engine stall / flameout
  • limit max N1/N2
  • Maintain air bleed requirement

computes N2 correction according to bleed

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5
Q

What can limit N2 independently from FADEC?

A

Overspeed Governor
Opens the Fuel Bypass Valve to limit N2 ico: malfunction

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6
Q

Fuel Hydraulic Signals control
LPTCC valves
HPTCC valves
RACC system (MTC neo)
VSVs
VBVs

What do the VSVs and VBVs do?

A

LP Turbine Clearance Control
HP Turbine Clearance Control
Rotor Active Clearance Control
Modulated Turbince Cooling

Variable Stator Vanes
* Maintain optimum compressor efficiency
* Adequate stall margin
* Fully closed at start
* Fully open at high thrust

Vbv Variable Bleed Valves
* Upstream of HP compressor
* Setting depends on inlet temp and N2
* Full open for start
* Full closed for high thrust

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7
Q

IDG cooling- FADEC /FRV controls flow

What target IDG temp?
What happens if hot oil but only low thrust / airflow?

If it gets hotter?
Hotter still?

When does the FRV close?

A
  • Mixes hot fuel with cold to maintain below 100ºC
  • At low thrust, and hot oil, cooling fuel returned to tank (300kg/h)
  • Increasing temp: ECU increases min N2
  • Further increasing: FADEC increases FF to tank (to 600 kg/h)
  • engine shut down
  • TO / CLB
  • Wing tank level under 300kg
  • Surge tank overflow
    • Except on ground
  • Gravity feed
  • Wing tank temp over 52.5ºC (max JetA1 54ºC)
    • Except on ground
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8
Q

Five components and lay out of the oil system?

A

Components
* Tank
* Lub/scavenge pumps
* Fuel/oil heat exchanger
* Filters, chip detectors,
* pressure relief + bypass valve

Layout
* Engine > Scavenge > Filter > Heater > Exchanger > Tank
* Tank > Pump > Filter (bypass) > Sensors > Bearing+gearbox

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9
Q

Cooling system, all controlled by FADEC via the HMU - what are the 3 systems and their functions?

A

RACC Rotor Active Clearance Control (compressors)
* FADEC via HMU
* Controls clearance between HP compressor rotors and stator case
* 5th stage compressor bleed
* Highest clearance when RACC valve closed

HPTCC system (turbines)
* FADEC via HMU
* Modulates HP compressor bleed flow
* Optimises HP turbine performance
* Reduces EGT

LPTCC
* FADEC via HMU
* Modulates fan bleed airflow (cooling)

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10
Q

How many SECs required to send a reverse signal to engine?

One or both gear compressed to activate?

A

Just the one

Both gear compressed

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11
Q

Reverser protection: when will auto restow engage?

When will idle protection engage?

A

Auto Restow
* If one door unstowed when reverse not selected
* Ground only, unless TO (N1 > 70%)

** Idle Protection**
* Idle thrust selected if reverse not selected and
* 4 doors unstowed
* 1 door unstowed/unknown with hydraulic pressure detected

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12
Q

What supplies igniter A when in EMER ELEC?

A

Igniter A supplied by STAT INV BUS when operative

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13
Q

On the first autostart, only one igniter is used (both for next start after a failure)

When does the igniter engage / disengage?

Above what elevation will both igniters engage on the ground?

Under which three circumstances will automatic continuous ignition engage?

A

N2 16% until 50%

Above 10,000 ft
Both igniters whenever in the air

  • EIU failure
  • Flame out
  • Ignition delay in start
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14
Q

What faults can FADEC detect during a start?

Abort Sequence?

A
  • Hot start (insufficient air flow to cool combustion chamber)
  • Hung start (light but no accel)
  • Stall
  • Failed light
  • Low start air pressure
  • Starter time exceeded
  • Thrust lever not at idle

Abort Sequence

  • Closes HP valve and start valve
  • Turns off ignition
  • Dry crank
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15
Q

Start sequence?

A
  • Pack valves close (reopen after 30s if no start)
  • LP Fuel opens
  • Start valve opens
  • Ignition @ N2 16% (immediately in flight)
  • HP valves @ N2 22% (15% in flight) (20% neo)
  • N2 50% (63% neo)
    • Start valve closes
    • Ignition stops (on ground) (55% neo)
    • Pack valves reopen after 30s
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16
Q

What decides if windmilling is fast enough for a start, or assistance required?

A

FADEC

17
Q

Manual Start Sequence?

A
  • IGN/START
  • MAN START pb sw ON
  • ENG MASTER to ON
  • ECAM warnings still given but no auto Abort
    • Except on ground if EGT overheat before 50% N2
18
Q

When will oil quantity flash?
When will it turn amber?

Oil pressure range
When will it flash (upper/lower)?
When does it turn red?

A

3.25 qt (1.35 neo)
3 qt

  • 0-100 PSI
  • Pulses over 90 (until 85)
  • Pulses under 16 PSI (until 20)
  • Red- 0-13 PSI
19
Q

When does the starter inlet pressure turn amber?

What is the nacelle advisory temp?

A

Below 21 PSI

240ºC

20
Q

Limitations
Ceo / Neo temperature limits?

A

CEO
* TOGA 5 min 950ºC
* OEI 10 min
* MCT 915ºC
* Starting 725ºC

NEO
* TOGA 5 min 1060ºC
* OEI 10 min
* MCT 1025ºC
* Starting 750ºC (flight 875ºC)

21
Q

Limitations

Ceo / Neo Max N1 + N2?

A

CEO: 104%, 105%
NEO: 101%, 116%

22
Q

Limitations
Max and min oil temp (same for ceo and neo)
Minimum oil temp on take off?

Minimum oil quantities?

A
  • 140ºC max cont
  • 155ºC for 15 mins
  • Starting -40ºC
  • Before TO: -10ºC (19ºC neo)

9.5 qt + 0.5 qt / hr
8.9 qt + 0.45 qt /hr (neo, min 10.6)

23
Q

Limitations
Minimum Oil Pressure
CEO/NEO

A

CEO min 13 PSI,
Max 90 PSI @ Max N2

NEO max 130 PSI
(145 PSI if below 50ºC)

24
Q

How long pause between ground starts on CEO / NEO?

N2 must be under what before starting with assistance?

A

20 sec ceo
60 sec neo

15 min after four fails (ceo)
15 min after three fails (neo)

N2 20% or less (63% neo)

25
Q

Min / Max flex temperatures?

A

Minimum TREF
A319: ISA + 30
A320: ISA + 29
A321: ISA + 15

TREF MAX
A319: ISA + 60
A320: ISA + 53/55neo
A321: ISA + 52

26
Q

Neo engine crosswind limits?

A

45 kt on ground
35 kt on takeoff (hence lower Xwind limit)

27
Q

What activates approach idle?

A

Config 3 or FULL or GEAR DN

28
Q
A

Technical (20 decks)

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